For 3-dimensional (3D) or 4-dimensional (4D) image data, a projection function that performs the mapping onto a 2-dimensional (2D) viewing plane of the display is needed. Common visualization techniques include displaying of planar cuts through (i.e. cross-sections of) the image data, projection techniques such as the maximum intensity projections (MIP) and volume rendering techniques based on transfer functions. Other techniques are planar and multiplanar reformats (MPR) described, e.g., in S. E. J. Connor and C. Flis, “The contribution of high-resolution multiplanar reformats of the skull base to the detection of skull-base fractures”, Clinical Radiology, Volume 60, Issue 8, 2005, Pages 878-885, and their generalization—curved planar reformation (CPR)—described, e.g., in Armin Kanitsar, Dominik Fleischmann, Rainer Wegenkittl, Petr Felkel, and Meister Eduard Gröller, CPR—curved planar reformation, Proceedings of the conference on Visualization '02 Boston, Mass., SESSION: Session P1: medical visualization Pages: 37-44 (also available at http://www.cg.tuwien.ac.at/research/publications/2002/kanitsar-2002-CPRX/TR-186-2-02-06 Paper.pdf), hereinafter referred to as Ref. 1. The goal of CPR is to make a tubular structure visible in its entire length within a single image. To this end, the centerline of the structure is obtained. The centerline and an arbitrary vector of interest selected by the user determine a re-sampling surface, as described in the introduction to section 3 CPR Methods of Ref. 1. The re-sampled data may be visualized using a projected CPR, stretched CPR or straightened CPR, as described in, respectively, section 3.1, 3.2, or 3.3 of Ref. 1.
The problem of the method described in Ref. 1 is that it is based on the centerline determination and thus the method is designed specifically for tubular structures and cannot be easily adapted for visualizing other objects such the human heart or brain.